To promote its new song from platinum-selling country music artist Hunter Hayes and Grammy winner Jason Mraz on Tuesday, Warner Music Group didn’t book its stars on “Good Morning America” or “Late Night With Jimmy Fallon.”

It made a video for YouTube.

YouTube has elbowed out radio, MTV, Yahoo and Myspace as the leading way to reach young music listeners, and some of its personalities have emerged as tastemakers.

“For teens through age 24, YouTube is where people listen to the most music,” said David Bakula, a senior vice president at audience measurement firm Nielsen. “It’s ahead of radio; it’s ahead of things like Pandora … or any other apps that they might use.”

For the record company, the value of the music video is largely promotional, much like traditional radio.

Although YouTube doesn’t sell music, it can expose a song to its 1 billion monthly users. If the song is a hit, some portion of the viewers will spring for a download from iTunes, Amazon or a similar service. And even if they don’t buy the song, YouTube and the record company share in the revenue from ads that accompany each video.

The idea for the collaboration was hatched at a dinner last March attended by executives of Warner Music and YouTube, a unit of Google Inc., who were attending the South by Southwest music and media conference in Austin, Texas.

Warner Music executives were looking for ways to reach consumers known as Generation C — a term Google uses to describe people ages 18 to 34 who watch online video, visit social networks and blogs, and use tablets and smartphones.

The resulting musical collaboration served as the soundtrack for “The Hunter Hayes YouTube Orchestra featuring Jason Mraz,” which debuts exclusively on YouTube, before the anticipated release of the official music video this month.